Loss of water from expansion tank - advice wanted

Technical questions and answers about the Mazda Bongo

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coco bongo

Post by coco bongo » Sat Mar 29, 2008 12:38 am

A shame when such a lovely motor goes this way, it's almost like a time bomb. When it's had it's time, thats it.

It's just a case of finding a good bit of cash, A fantastic mechanic who wont cock it up, and replace most of the cooling system. A process of elimination.

Im sure that once they are done, they're good to go for ages. I have heard of a few members that have had no problems what so ever with overheating.
BUT.. is it just a matter of time before it happens to them. :?:

Thank god that Bongo Fury is here to help Bongo owners know they are not alone when this happens. I owe you guy's loads.

And also there is the thing with the Importers of Bongos, how much do they do to the vehicle when they get it in. They say they do this and do that, But do they?. Its all about profit for them at the end of the day, and some dont really care what happens to it, as long as it isn't in the first 3 months. Not saying they are all like that, but you still have to double check the work they have supposedly done.
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Post by bigdaddycain » Sat Mar 29, 2008 12:42 am

I agree wholeheartedly with both of you,(MM & TGP)but there are plenty of instances,where an iron block can be mated with an alloy head,and the head gasket is considered to be the first line of defence (if caught early enough) before complete meltdown of the actual head....

Take my earlier example for instance, with the cossie the block is a re-hash of the old "pinto" block developed in the sixties,the 16V head is alloy and can be mated perfectly with that,2 headgaskets blew (uprated gaskets at that) without any damage whatsoever to the cylinder head...
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Post by The Great Pretender » Sat Mar 29, 2008 12:49 am

And bdc dont forget the Triumph Dolamite after they realised it overheated and nackered heads what did they do :shock: They made it into a V8 for the Stag. :roll: :roll: :roll:
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Post by bigdaddycain » Sat Mar 29, 2008 12:52 am

coco bongo wrote: BUT.. is it just a matter of time before it happens to them. :?:
I suspect not coco...The usual ultimate death knoll for most diesels is lack of compression due to bore wear... I last had that on a diesel fiesta with 310,000 miles on the clock... My bongo is still quite a bit less than 100k(barely run -in) My other diesel (ford focus) has well over a quarter of a million on the clock,and the lowest compression is 96% on cylinder 3! :lol:
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Post by bigdaddycain » Sat Mar 29, 2008 12:53 am

The Great Pretender wrote:And bdc dont forget the Triumph Dolamite after they realised it overheated and nackered heads what did they do :shock: They made it into a V8 for the Stag. :roll: :roll: :roll:
:lol: Yeah, strap 2 dodgy four pots together,and turn it into a v8! :lol:
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Post by The Great Pretender » Sat Mar 29, 2008 12:58 am

Totally changing the conversation Steve what is the width of your worktop in the Bongo?
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Post by bigdaddycain » Sat Mar 29, 2008 1:13 am

Hang on...i'll nip out and measure it.....

Ok, i'm back....BRRRR, its cold out :shock: 19" or 49 cm... :wink:
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Post by haydn callow » Sat Mar 29, 2008 9:38 am

TGP,,,,This coolant not draining out of the tank when you removed the stat....This is exactly what happened when we were simulating leaks testing the alarm...very strange..(we reported this on here)..However as with our trials I notice that the level in the tank has dropped by more than 1 inch. This is also as we found it and every time enough coolant was lost from the tank to set the alarm off.
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Post by The Great Pretender » Sat Mar 29, 2008 2:04 pm

Thanks for that Steve.

I realise that Haydn and the coolant loss alarm is a great idea, the fact that so mutch coolant can be lost and the system air locks is a concern.
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Post by haydn callow » Sat Mar 29, 2008 2:17 pm

TGP...even with the engine running and up to full pressure when I opened the drain on the bottom of the rad to try and simulate a leak down there, the tank level dropped about one inch and then ALL the coolant drained slowley out of the system. I ended up with the header tank much the same level as yours and a system full of froth. (impeller drawing air in)
Even then the temp gauge did not move and in the end I chickened out.
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Re: Loss of water from expansion tank - advice wanted

Post by Simon Jones » Tue Apr 08, 2008 11:04 pm

Just to give you al update on the situation. I've only been able to put in a few hours here & there after work & between showers/snow/hail etc. The basic plan is to remove the head & check for signs of gasket failure, then fit new gaskets, thermostat, water pump and Flippa's hoses. If necessary, I'll change the radiator too, but that can be done after the tricky bits are back together.

I've removed all the ancillaries from the head. This is quite a time consuming process: one of the nuts on the turbo wouldn't budge, so had to struggle to get the exhaust manifold nuts off. The cambelt cover is a sod to get off unless you remove the pipe from the intercooler. It helps to have lots of boxes & compartments to put all the bits into.

Someone has previously blanked the EGR, it almost looks like someone has welded the valve closed. It is a bit messy, so I'll have a closer look once it cleaned up. There is huge amount of goo in the inlet manifold, but I understand this is quite normal for a diesel.

The head is now ready to come off, so hopefully I will be able to start inspecting it & cleaning it up tomorrow. Fortunately, I have a very useful chap as a neighbour who has lots of gear in his workshop including a milling machine should we find it needs skimming. All the spare bits should be here on Friday, so with a bit of luck I can start re-assembling on Saturday.
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Re: Loss of water from expansion tank - advice wanted

Post by dandywarhol » Tue Apr 08, 2008 11:54 pm

I'd get it crack tested by a professional too - sometimes hard to spot one......
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Re: Loss of water from expansion tank - advice wanted

Post by The Great Pretender » Wed Apr 09, 2008 12:01 am

dandywarhol wrote:I'd get it crack tested by a professional too - sometimes hard to spot one......
Where would you expect to find the crack dandy?
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Re: Loss of water from expansion tank - advice wanted

Post by dandywarhol » Wed Apr 09, 2008 8:37 am

Don't know where it would show up on a Bongo head TGP - I haven't seen a cracked one but I've seen cracks on alloy heads between the water jacket and combustion chamber after a dye test. Probably caused by trapped air pocketing in the head.
A good machine shop should be able to pressure test a head and check for air bubbles in a water tank.

I just think it's worth doing if the heads off and is suspect.
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Re: Loss of water from expansion tank - advice wanted

Post by coco bongo » Wed Apr 09, 2008 12:26 pm

dandywarhol wrote:
I just think it's worth doing if the heads off and is suspect.
I agree with Dandy on this one, as you have just spent the time stripping it all apart, a skim and pressure test will cost about £60 ish. £30 for each basically.

So, you will definitely know that the head is good or not for £30. I wouldnt cut corners on this job mate, as you've gone to so much work :wink: . A new set of head bolts too wouldnt be a bad idea.
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